1. Introductory Remarks
In the telephone system post-divestiture environment, complex regulatory tariffs have been mandated and/or inter-carrier contracts have been negotiated between carriers which (a) regulate the way in which traffic is to be routed between them and (b) specify the rates at which various types of traffic are to be charged. It is often of financial advantage to mis-route calls in violation of these existing regulatory tariffs and/or established inter-carrier contracts. The common name for this manipulation is “arbitrage”. The intent of those perpetrating this mis-routing is to take advantage of lower rates associated with the delivery of telephone traffic via other than the proper routes. Confirming the presence of arbitrage and proper billing is often difficult due to the fact that call routing information is often missing or incomplete.
2. Definitions
In general, the following definitions are common in the telephone industry, but are included herein for completeness and clarity of explanation. They define the meanings of these terms as used in the Present Patent Document.
Access Traffic
A compensation mechanism governed by tariffs and/or contracts for message traffic carried by interexchange carriers (IXC) and exchanged between the IXC's and local exchange carriers (LEC's), independent local exchange carrier (ILEC's), and competitive local exchange carrier (CLEC's). This type of traffic is generally carried over a type of telephone trunk called a Feature Group D trunk or FG-D trunk, and typically carries the highest per-minute charge. Under access traffic, IXC's pay the other carriers for each Minute of Use (MOU) of traffic destined to the IXC or originating from the IXC.
ACM Timestamp
The time at which the telephone being called began alerting the user (e.g. ringing).
Address Complete Message (ACM)
The Address Complete Message (ACM) is used to acknowledge receipt of an initial address message (IAM) and to indicate that the called party is being alerted (e.g. via ringing).
ANM Timestamp
The time the operator of the telephone being called answered the telephone.
Answer Message (ANM)
The Answer Message (ANM) is used to indicate that the user called has answered, end to end connection is established, and a conversation takes place.
Arbitrage
As used herein and as commonly used in the telephone industry, it is the mis-routing of inter-carrier telephone calls in such a way as to violate existing regulatory tariffs and/or established inter-carrier contracts. The purpose of such mis-routing is typically to take advantage of lower rates associated with the delivery of telephone traffic via routes other than those established and required by such tariffs and contracts and as such may be fraudulent. Arbitrage typically occurs via the following techniques: (1) interexchange carrier (IXC) access traffic delivered via competitive local exchange carriers (CLEC's) and (2) transit traffic delivered via non-transit trunks
Backward Interwork Parameter
An indicator as to whether Signaling System 7 (SS7) and non-SS7 inter-working was encountered ahead of this point in the call.
Call Detail Record (CDR)
A collection of messages comprising parameters and time-stamps associated with each call which provide detail regarding the call origin, destination, and other details.
Called Number
The telephone number dialed by the calling user.
Calling Number
The telephone number of the user making the call.
Carrier Identification Code (CIC)
Parameters contained within the Signaling System 7 (SS7) Initial Address Message (IAM) message which can be used to identify the requested interexchange carrier (IXC).
Carrier Identification Code Parameter
The number identifying the interexchange carrier (IXC) selected by the Local Exchange Carrier.
Charge Number
The telephone number to which the call is charged. Typically it is the telephone number of the calling telephone.
Competitive Local Exchange Carriers (CLEC)
A local exchange carrier (LEC) but specifically referring to one that competes with the incumbent local exchange carrier (LEC).
Destination Point Code (DPC)
The Signaling System 7 (SS7) node [e.g switching office or Signaling Transfer Point (STP)] that the message is being sent to.
eo
A switching office normally referred to as an end office or “eo” to which telephones (from homes or businesses) are connected via wires called “loops”.
Feature Group D Trunk (FG-D Trunk)
A type of telephone trunk. See Access Traffic.
Forward Interwork Parameter
An indicator as to whether Signaling System 7 (SS7) and non-SS7 inter-working was encountered prior to the point in the call where the parameter is observed.
IAM Timestamp
The time the trunk was seized for transmission of an SS7 message.
Independent Local Exchange Carriers (ILEC)
Generally refers to a local exchange carrier (LEC) which co-existed with a local exchange carrier owned by the Regional Bell Operating Companies.
Initial Address Message (IAM)
The Initial Address Message (IAM) is used to indicate the desire to set up a call. A trunk is seized and “reserved” for use in the call.
Interconnect Carrier
Any carrier that interconnects with the local exchange carrier (LEC).
Interexchange Carriers (IXC)
An interexchange carrier (IXC) transports calls from one local exchange carrier (LEC) to another, or possibly the same LEC, throughout the IXC's serving area. The IXC's serving area would typically span more than one local access transport area (LATA), and the IXC receives messages from and delivers messages to local exchange carriers (LEC's, CLEC's, and ILEC's) and other interchange carriers (IXC's). Calls that span local area transport areas (LATA's—geographical regions defined at divestiture) typically must use an IXC.
IXC Trunk
A trunk that comes from an interexchange carrier to a local exchange carrier.
Jurisdiction Indicator Parameter
A parameter contained in SS7 messages which, if available, indicates the geographic origin of a call.
Link Monitoring System (LMS)
A system that can be used to collect Call Detail Records (CDR's) by monitoring SS7 links.
Local Access Transport Area (LATA)
The geographic area within which a local exchange carrier (LEC) provides service is typically divided into various areas referred to as local access transport areas (LATA's).
Local Exchange Carrier (LEC)
A local exchange carrier (LEC) is a telephone service provider that provides telephone service to its customers in a specific geographical serving area. A local exchange carrier (LEC) would typically be a local telephone company.
Local Exchange Routing Guide (LERG)
A document defining the specific local access transport area (LATA) within which a given telephone number is located.
Location Routing Number (LRN)
A number obtained from the database at the service control point (SCP). The SCP converts the called number into the LRN which is the number used by the network to get the call to its final destination.
Loop
Telephones are connected (from homes or businesses) via wires called “loops” to a switching office normally referred to as an end office or “eo”.
Meet-Point Billing
Traffic exchanged between interexchange carriers (IXC's) and independent local exchange carriers (ILEC's) destined for local exchange carrier (LEC) customers (in cases where the IXC does not directly interconnect with the LEC) is governed by tariffs and/or contracts, using a compensation mechanism referred to as meet-point billing. Under meet-point billing, IXC's pay the ILEC a fee, part of which is subsequently paid by the ILEC to the LEC for each Minute of Use (MOU) of traffic between the IXC and the LEC.
Minute of Use (MOU)
For billing purposes a measure of the time which a given carrier's resources are consumed providing a given service.
Numbering Plan Address (NPA)
More commonly known as the area code of the telephone number.
NPANXX
The numbering plan address (i.e., the area code) plus the next three digits of the telephone number.
Originating Point Code (OPC)
The Signaling System 7 (SS7) node [e.g. switching office or Signaling Transfer Point (STP)] that is sending the message.
Reciprocal Compensation
Under reciprocal compensation, carriers pay each other a usage fee for each Minute of Use (MOU) of traffic delivered from their network to the other carrier's network. This message traffic is typically traffic exchanged between various local exchange carriers (LEC's) and their competitive local exchange carriers (CLEC's) and independent local exchange carriers (LEC's). This type of traffic is generally carried over a type of telephone trunk called a local trunk.
Release Complete Message (RLC)
The Release Complete Message (RLC) is sent when the second of the two connected parties hangs up. At that point the trunk is released.
Release Message (REL)
The Release Message (REL) indicates that the first of the two connected parties has hung up.
REL Timestamp
The time the operator of the first telephone to hang up did so.
Remote Site Processors
A device used to consolidate partial Call Detail Records (CDR's) into complete CDR's.
RLC Timestamp
The time the operator of the second telephone to hang up did so.
Service Control Point (SCP)
A network database used to translate called numbers into local routing number which translates the called number in the location routing number (LRN).
Signaling Transfer Points (STP's)
At the heart of the SS7 network are packet switches known as Signaling Transfer Points (STP's). STP's are deployed in pairs in the North American SS7 network to provide communication path redundancy. Different carriers own a portion of the SS7 network and interconnect their end offices (eo's) and tandem's to the overall SS7 network so as to enable end-to-end communication between carriers.
SS7 Links
The communication links over which Signaling System 7 (SS7) traffic is carried.
SS7 Network
The Signaling System 7 (SS7) messages are transported over a secure data network referred to as the “SS7 network”. The SS7 network comprises various SS7 Links along with Signaling Transfer Points (STP's).
SS7 Protocol
To perform the task of call setup and tear down when multiple end offices (eo's) are involved, switching offices communicate with each other using a signaling protocol referred to as Signaling System 7 (SS7), carried over SS7 links. SS7 messages are used in specific sequences to perform various tasks required to establish telephone connections. Telephone calls between two customers connected to the same eo will be handled by the application logic contained in the eo, and will not require the use of the SS7 protocol.
Tandem
In certain cases, for example two towns that are somewhat far apart, a type of switching center called a “tandem” is involved in establishing connectivity between two customers.
TCIC
Trunk Circuit Identification Code. Between any two telephone switches there may a trunk group which comprises several trunks. These trunks are identified via the TCIC.
Transit Network Selection (TNS)
Parameters contained within the Signaling System 7 (SS7) Initial Address Message (IAM) message which can be used to identify the requested interexchange carrier (IXC).
Transit Traffic
Traffic that goes thru a LEC network but does not originate or terminate in that LEC and uses trunks other than those specifically designated for such traffic.
Trunk
When telephones are served from different eo's (e.g. in different towns), they are interconnected via wires called “trunks” between the eo's.
Wide Area Network (WAN)
A communication network serving a large geographical area of interest.
4. Discussion
Previous methods for the determination of telephone traffic routing have been based upon a single call sample, e.g. a call record obtained at the point where the call originates or at the point where the call terminates. The information available within a single call record has limitations due to the fact that critical routing information may be (a) missing or (b) incorrect. These techniques have proven to be ineffective at determining the presence of arbitrage. Since in typical arbitrage situations, the local exchange carrier is under billing the interexchange carriers, there is a great financial incentive for the local exchange carrier to detect and stop arbitrage, and since previous methods are both unreliable and labor intensive, there is a great need for improved means for detecting arbitrage.